This invention relates to coated paperboard which may be used within the beverage industry to provide containers for citrus and fruit juices, milk, and other liquid and non-liquid food products. A variety of coating layers are known to be used to provide useful properties to the resulting paperboard laminate. For instance, within the citrus juice industry paperboard cartons have coatings designed to provide an oxygen barrier. The incorporation of oxygen barriers into a laminate structure helps preserve Vitamin C content against oxidative loss and contributes to a longer product shelf life.
In addition, juice cartons are prone to scalping of essential oils in the carton's contents by the skin or product contact layer of the laminated board. As such, barrier coatings which provide increased resistance to scalping are also desirable.
Extruded nylon has been used as one layer of a multi-component laminated structure for a barrier board. One such barrier board which provides for oxygen barrier properties and reduces essential oil loss is disclosed in Thompson et al, U.S. Pat. No. 4,777,088.
Brown et al, U.S. Pat. No. 4,753,832, also discloses a nylon oxygen barrier layer as part of a laminated structure. The Brown et al layer provides a skin layer of glycol-modified polyethylene terephathalate (PET-G).
Parks et al, U.S. Pat. No. 6,149,993, discloses a layer of amorphous nylon as an oxygen barrier structure. Amorphous nylon has relatively low strength as compared to Nylon-6 and other semi-crystalline nylon structures. The Park et al reference proposes that the oxygen barrier properties of amorphous nylon are equivalent to the barrier properties of laminated structures containing ethylene vinyl alcohol (EVOH).
An EVOH barrier laminated structure may be seen in reference to the Gibbons et al, U.S. Pat. No. 4,701,360, in which EVOH is provided as a heat-sealable oxygen barrier that offers resistance to scalping when present as the skin layer of a board laminate.
While the art provides for a variety of laminated barriers for cartons, there remains for room for variation and improvement within the art.